Composition and sheet material for inhibition of corrosion of metals



COMEOSITION AND SHEET MATERIAL FOR INHIBITION OF CORROSION F METALS Murray Senlrus, Western Springs, 111., assignor to panbert Chemical Company, a corporation of Illinois No Drawing. Application September 15, 1956, Serial No. 185,142

14 Claims. (Cl. 21-2.5)

My invention relates to improvements in corrosion inhibitors and more particularly to corrosion inhibitors for use in conjunction with ferrous metal surfaces which are subject to attack by the elements normally existing in the atmosphere.

In the U. S. patent of Edward A. Schwoegler and Clemens A. Hutter, No. 2,521,311, dated September 5, 1950, efiective metal corrosion inhibiting compositions are disclosed containing organic amides and inorganic metal nitrites. As is disclosed in said patent, a synergistic effect is secured by virtue of the conjoint use of the aforesaid two types of materials.

Among the inorganic nitrites which can be utilized pursuant to the teachings of the aforesaid patent are the alkali metal nitrites, including ammonium nitrite, sodium nitrite, potassium nitrite and lithium nitrite. Of particular utility are the water-soluble nitrites. Other nitrites can be utilized including those which are soluble.

in organic solvents and those which are mutually soluble with the organic amides in organic or other solvent media. i

As described in the aforementioned patent, among the amides which can be used in combination with the nitrites are the mono-amides, diamides, and polyamides. The term mono-amide is meant to include organic compounds having the general formula RCONHz, where R is an aliphatic group having from 1-25 or more carbon atoms. These include such amides as acetamide, propionamide, N-butyramide, N-valeramide, stearamide, palmitylamide, fatty acid amides and the like. Although less activity results when R is alicyclic, aromatic or mixed aliphatic aromatic, amides of this type can be used. For example,

the amide can be benzamide or aromatic acid amides of the type of benzensulfonic acid amide, toluenesulfonic acid amide, naphthalenesulfonic acid amide and the like. The most suitable amides are the diarnides, which can be represented by the general formula RzNCONRz, where R can be hydrogen or an organic radical of the type previously described for the monoamide formula. Illustrative of suitable diamides are urea, guanidine, biuret, and the like, or N-substituted ureas and unsymmetrical ureas such as N,N-dibutyl urea, N-butyl urea, N-propyl urea, dimethyl urea, tertiary butyl urea, tertiary amyl urea, ethyl butyl urea and the like. Of particular utility is urea.

As is further described in the foregoing patent, good results are obtained when the aforesaid compounds are utilized in the ratio of one part of the inorganic nitrite to from about 0.05-20 parts of the amides, said parts being by weight, and particularly advantageous results are obtained by the employment of substantially equal parts by weight of the inorganic nitrite and the organic amide.

My invention is based upon the discovery that the functioning of the aforesaid compositions, in relation to the inhibition of corrosion of ferrous objects, is substantially improved by the incorporation therein or conjoint use therewith of amine and ammonium salts of car'- States atent Water boxylic acids containing from. 6 to 18 carbon atoms. The action of the said salts appears to synergize the activity of the organic amide-inorganic nitrite compositions so as to bring about a marked enhancement of the corrosion inhibiting properties of the latter compositions.

The carboxylic acids whose ammonium and amine salts are utilized in accordance with the present invention include aliphatic, araliphatic and aromatic straight chain and branched chain monocarboxylic and dicarboxylic acids. The aromatic acids may, for example, be represented by the formula (R)vAI'-(COOH)n, where R is halogen (particularly chlorine or bro-mine), nitro, hydroxy, and alkyl and alkenyl containing from 1 to 5 carbon atoms, Ar is an aromatic hydrocarbon radical, v is zero to 2, and n is 1 to 2. Typical illustrative examples of such acids are caproic, caprylic, 2-ethyl hexoic, benzoic, naphthoic, anthraquinoic, phenyl acetic, phydroxy phenyl acetic, o-hydroxy phenyl acetic, lauric, palmitic, stearic, succinic, itaconic, aconitic, phthalic, adipic, salicyclic, hydroxy benzoic, pimelic, sebacic, hexahydrobenzoic acid, mucic acid, and azelaic acid.

As I have stated above, the carboxylic acids are utilized in the form of their ammonium or amine salts. The amines can be selected from a large group and comprise aliphatic, araliphatic and aromatic straight chain and ylamine; a-methyl-fl-hydroxyisopropylamine; and the like.

Any of the aforementioned carboxylic acids can be utilized in the form of their ammonium salts or in the form of salts of any of the aforementioned -illustrated amines. Of especial utility is the -di-isopropylamine salt of 2-.ethylhexoic acid.

The following examples are illustrative of corrosion .inhibiting compositions made in accordance with my invention. It will be understood that various changes may be made therein in relation to proportions of the ingredients and numerous other compositions can readily be evolved in the light of the teachings disclosed herein. Said compositions may be utilized, among other ways, to impregnate carriers or solid bodies of various types to deposit therein the solids comprising the corrosion inhibiting compositions. All parts given are by weight. Example 1 Sodium nitrite 30 Urea 30 Ammonium benzoate 30 Water -Q. 60

Example 2 r Sodium nitriteuu; Q it 6 Acetamide 12 Di-isopropyl amine .salt of benzoic acid 12 3 Example 3 Potassium nitrite 12 Stearamide 18 Triethylamine salt of 2-ethyl hexoic acid 20 Water 45 Isobutyl alcohol 45 Example 4 Sodium nitrite 4 Guanidine 18 Ammonium salt of 2-ethyl hexoic acid 15 Water 85 Example 5 Ammonium nitrite 8 Benzene sulfonic acid amide 8 Di-isopropyl amine salt of naththoic acid Water 95 Example 6 Ammonium nitrite 20 Urea 2O Triethylamine salt of phthalic acid 10 Water 80 Example 7 Ammonium nitrite N-butyl ur 8 Di-isopropyl amine salt of succinic acid 18 Water 100 Example 8 Sodium nitrite..- Urea 20 Di-isopropyl amine salt of 2-ethyl hexoic acid 30 Water 70 Example 9 Sodium nitri 30 Urea 30 Di-isopropyl amine salt of benzoic acid 30 Water 60 Example 10 Sodium nitri 30 Urea 3O Ammonium salt of phenyl acetic acid 30 Water 70 The three components comprising the corrosion inhibiting compositions which are utilized in accordance with my invention can be employed in varying proportions. Good results are obtained, for example, where, for each part of inorganic nitrite, from 0.05 to 20 parts each of the organic amide and the amine or ammonium salt of the carboxylic acid are employed, said parts being by weight. Especially advantageous results are obtained where the ingredients are employed in proportions stock, finely divided particles of relatively inert material, and the like, in any one of several Ways disclosed, for example, in the aforementioned patent. Thus, all of the ingredients may be dissolved in a suitable solvent, for instance, water, or an organic solvent or a mixture of solvents, and the carrier impregnated with the solution after which the solvent material may be evaporated. Alternatively, the corrosion inhibiting composition may be utilized in the form of a dispersion or emulsion and deposited into or upon a carrier by dipping, brushing, spraying and other ways known in the art. While, in commercial practice, it is desirable that all of the ingredients comprising the corrosion inhibiting compositions of the present invention be deposited on or into the carrier from a single solution or dispersion or the like, it will be appreciated that such procedure need not be followed. Thus, for example, the inorganic nitrite may initially be deposited in or upon the carrier after which the organic amide may be deposited followed by the deposition of the amine or ammonium salt of the carboxylic acid, or the order of the deposition ofthe aforesaid ingredients may be altered in any way desired. The important thing is that all three of said ingredients be present so that they can exert their conjoint effects.

As described in the aforesaid patent, it is frequently desirable to coat one side of a sheet of paper or other absorbent cellulosic or fabric material or the like, which has been impregnated with a corrosion inhibiting composition, with a water-repellent or moistureproof material for the purposes of preventing too rapid dissipation of the corrosion inhibiting composition and to insure against undue moisture absorption by said carriers where one or more of the ingredients of the corrosion inhibiting composition utilized is of a hygroscopic character. A number of water-repellent materials is readily available for use in this connection as, for example, waxes, such as microcrystalline waxes, asphaltums, soaps of normally solid fatty acids such as sodium stearate, and various other materials of this type. For a more detailed description thereof, and for a detailed description of various carriers and manners of utilizing in practical commercial ways corrosion inhibiting compositions of the type here involved, reference may be had to the aforementioned patcut and application as Well as to the application of Clemens A. Hutter, Serial No. 124,852, filed November 1, 1949, now Patent No. 2,534,201, dated December 12, 1950. The teachings and practices disclosed in said patent and applications can be and advantageously are utilized in the practice of my present invention.

What I claim as new and desire to protect by Letters Patent of the United States is: v

l. A vapor phase inhibiting composition for inhibiting corrosive attack on metal by elements normally existing in the atmosphere comprising, as essential ingredients, an

organic amide, an inorganic metal nitrite, and at least one member selected from the group consisting of amine and ammonium salts of carboxylic acids selected from amounting to substantially equal parts of inorganic nitrite and organic amide with a slightly greater propor tion of the amine or ammonium salt.

When the corrosion inhibiting composition is embodied or incorporated into a solid carrier or support member as, for example, a sheet of paper, a corrugated or other carton, a separator, or a wrapper or the like, good results are obtained where the corrosion inhibiting composition is present in a concentration of from about 0.1 to 5 or 10 grams per square foot of surface of the carrier sheet or the like. In the usual case, the corrosion inhibiting composition is very effective when it is present in or on the carrier or support member in the total amount of the order of about 2 to 4 grams per square foot. of sheet surface-area-to which the ferrous article to be protected is exposed.

The corrosion inhibiting composition may be incorporated into or upon a suitable carrier,'which may be sheet the group consisting of caproic, caprylic, 2-ethyl hexoic, phenyl acetic, p-hydroxy phenyl acetic, o-hy-droxy phenyl acetic, lauric, palmitic, stearic, succinic, itaconic, aconitic, phthalic, adipic, salicylic, hydroxy benzoic, pimelic, hexahydrobenzoic, mucic, azelaic; and aromatic acids represented by the formula (R)v-AI(COOH)n where R is selected from the group consisting of halogen, nitro, hy-

droxy and aliphatic hydrocarbon radicals containing from 1 to 5 carbon atoms, Ar is an aromatic hydrocarbon radical, v is zero to 2, and n is 1 to 2, said ingredients being present in the ratio of about 1 part by weight of said nitrite to 0.05-20 parts by weight each of said amide. and

said salt.

2. A vapor phase inhibiting composition for inhibiting corrosive attack on metal byelements normally existing in the atmosphere comprising, as essential ingredients, urea, a water-soluble inorganic nitrite, and at least, one

member selected from the group consisting of amine and ammonium salts of carboxylic acids selected from the group consisting of eaproic, caprylic, 2-ethyl hexoic, phenyl acetic, p-hydroxy phenyl acetic, o-hydroxy phenyl acetic, lauric, palmitic, stearic, succinic, itaconic, aconitic, phthalic, adipic, salicylic, hydroxy benzoic, pimelic, hexahydrobenzoic, mucic, azelaic; and aromatic acids represented by the formula (R)vAl(COOII)n where R is selected from the group consisting of halogen, nitro, hydroxy and aliphatic hydrocarbon radicals containing from 1 to 5 carbon atoms, Ar is an aromatic hydrocarbon radical, v is zero to 2, and n is 1 to 2, said ingredients being present in the. ratio of 1 part of said nitrite to 0.05-20 parts each of the urea and said carboxylic acid salt.

3. A vapor phase inhibiting composition of matter for inhibiting corrosive attack on metal by elements normally existing in the atmopshere comprising, as essential ingredients, 1 part alkali metal nitrite and 0.0520 parts each of urea and at least one member selected from the group consisting of amine and ammonium salts of caproic acid.

4. A vapor phase inhibiting composition for use in the inhibition of corrosive attack on metal by elements normally existing in the atmosphere comprising, as essential ingredients, urea, sodium nitrite, and at least one member selected from the group consisting of amine and ammonium salts of carboxylic acids selected from the group consisting of eaproic, caprylic, Z-ethyl hexoic, phenyl acetic, p-hydroxy phenyl acetic, o-hydroxy phenyl acetic, lauric, palmitic, stearic, succinic, itaconic, aconitic, phthalic, adipic, salicylic, hydroxy benzoic, pimelic, hexahydrobenzoic, mucic, azelaic; and aromatic acids represented by the formula (R)pAI-(COOH)n where R is selected from the group consisting of halogen, nitro, hydroxy and aliphatic hydrocarbon radicals containing from 1 to 5 carbon atoms, Ar is an aromatic hydrocarbon radical, v is zero to 2, and n .is 1 to 2, said ingredients being present in the ratio of 1 part of said nitrite to 0.05-20 parts each of the urea and said carboxylic acid salt.

5. A vapor phase inhibiting composition in accordance with claim 4, in which the carboxylic acid is 2-ethyl hexoic acid.

6. A vapor phase inhibiting composition in accordance with claim 4, in which the carboxylic acid is benzoic acid.

7. An article of manufacture for inhibiting the corrosion of metal by means of vapor phase inhibition comprising a solid carrier embodying therein an organic amide, an inorganic nitrite, and at least one member selected from the group consisting of amine and ammonium salts of carboxylic acids selected from the group consisting of eaproic, caprylic, 2-ethy1 hexoic, phenyl acetic, p-hydroxy phenyl acetic, o-hydroxy phenyl acetic, lauric, palmitic,

stearic, succinic, itaconic, aconitic, phthalic, adipic, salicylic, hydroxy benzoic, pimelic, hexahydrobenzoic, mucic, azelaic; and aromatic acids represented by the formula (R) v-AI(COOH)11. where R is selected from the group consisting of halogen, nitro, hydroxy and aliphatic hydrocarbon radicals containing from 1 to 5 carbon atoms, Ar is an aromatic hydrocarbon radical, v is zero to 2, and n is 1 to 2, said ingredients being present in the ratio of 1 part of said nitrite to 0.05-20 parts each of said amide and said carboxylic acid salt.

8. An article of manufacture for inhibiting the corrosion of metal by means of vapor phase inhibition comprising paper sheet stock impregnated with urea, an alkali metal nitrite, and at least one member selected from the group consisting of amine and ammonium salts of carboxylic acids selected from the group consisting of eaproic, caprylic, 2-ethyl hexoic, phenyl acetic, p-hydroxy phenyl acetic, o-hydroxy phenyl acetic, lauric, palmitic, stearic, succinic, itaconic, aconitic, phthalic, adipic, salicylic, hydroxy benzoic, pimelic, hexahydrobenzoic, mucic,

azelaic; and aromatic acids represented by the formula (R)vAI-(COOH)n where R is selected from the group consisting of halogen, nitro, hydroxy and aliphatic hydrocarbon radicals containing from 1 to 5 carbon atoms, Ar is an aromatic hydrocarbon radical, v is zero to 2, and n is 1 to 2, the urea, the alkali metal nitrite and the carboxylic acid salt each being present in an amount equal to at least 0.5 gram and the total of said ingredients being present in an amount of about 2 to about 4 grams per square foot of paper sheet surface area.

9. An article of manufacture for inhibiting the corrosion of metal by means of vapor phase inhibition comprising paper impregnated With urea, sodium nitrite, and di-isopropyl amine salt of caproic acid, the aforesaid ingredients being present in the ratio of 1 part of said nitrite to 0.05-20 parts each of the urea and the di-isopropyl amine salt of caproic acid.

10. An article of manufacture for inhibiting the corrosion of metal by means of vapor phase inhibition comprising paper sheet stock impregnated with urea, sodium nitrite, and di-isopropyl amine salt of 2-ethyl hexoic acid, the aforesaid ingredients being present in the ratio of 1 part of said nitrite to 0.0520 parts each of the urea and the di-isopropyl amine salt of 2-ethyl hexoic acid, one surface of said paper sheet stock carrying a backing comprising a layer of moisture-repellent material.

11. An article of manufacture in accordance with claim 9, in which the urea, sodium nitrite and di-isoppropyl amine salt of caproic acid are each present in amounts of at least 0.5 gram and the total of said ingredients is present in an amount of about 2 to about 4 grams per square foot of the paper sheet surface area.

12. A vapor phase inhibiting composition for use in the inhibition of corrosive attack on metal by elements normally existing in the atmosphere comprising, as essential ingredients, urea, sodium nitrite, and 2-hydroxyethylammonium benzoate, said ingredients being present in the ratio of about 1 part by Weight of said nitrite to 0.05-20 parts by weight each of said amide and said salt of benzoic acid.

13. An article of manufacture for inhibiting the corrosion of metal by means of vapor phase inhibition comprising paper sheet stock impregnated with urea, an alkali metal nitrite, and the 2-hydroxyethylammonium salt of benzoic acid, the urea, the alkali metal nitrite and the benzoic salt each being present in an amount equal to at least 0.5 grams and the total of said ingredients being present in an amount of about 2 to about 4 grams per square foot of paper sheet surface area.

14. An article of manufacture for inhibiting the corrosion of metal by means of vapor phase .inhibition comprising paper impregnated with urea, sodium nitrite and Z-hydroxyethylammonium benzoate, the aforesaid ingredients being present in the ratio of 1 part of said nitrite to 0.05-20 parts each of the urea and the 2-hydroxyethylammonium benzoate.

References Cited in the file of this patent UNITED STATES PATENTS 2,330,524 Shields Sept. 28, 1943 2,421,311 Schwoegler et a1. Sept. 5, 1950 2,629,649 Wachter Feb. 24, 1953 FOREIGN PATENTS 596,160 Great Britain Dec. 30, 1947 600,328 Great Britain Apr. 6, 1948 OTHER REFERENCES Baker et al.: Polar Type Rust Inhibitors, Industrial and Engineering Chemistry, vol. 40, December 1948, pp. 2338 to 2347. 

1. VAPOR PHASE INHIBITING COMPOSITION FOR INHIBITING CORROSIVE ATTACK ON METAL BY ELEMENTS NORMALLY EXISTING IN THE ATMOSPHERE COMPRISING, AS ESSENTIAL INGREIENTS, AN ORGANIC AMIDE, AN INORGANIC METAL NITRITE, AND AT LEAST ONE MEMBER SELECTED FROM THE GROUP CONSISTING OF AMINE AND AMMONIUM SALTS OF CARBOXYLIC ACIDS SELECTED FROM THE GROUP CONSISTING OF CAPROIC, CAPRYLIC, 2-ETHYL HEXOIC, PHENYL ACETIC, P-HYDROXY PHENYL ACETIC, O-HYDROXY PHENYL ACETIC, LAURIC, PALMITIC, STEARIC, ITACONIC, ACONITIC, PHTHALIC, ADIPIC, SALICYLIC, HYDROXY BENZOIC, PIMELIC, HEXAHYDROBENZOIC, MUCIC, AZELAIC; AND AROMATIC ACIDS REPRESENTED BY THE FORMULA (R)V-AR-(COOH)N WHERE R IS SELECTED FROM THE GROUP CONSISTING OF HALOGEN, NITRO, HYDROXY AND ALIPHATIC HYDROCARBON RADICALS CONTAINING FROM 1 TO 5 CARBON ATOMS, AR IS AN AROMATIC HYDROCARBON RADICAL, V IS ZERO TO
 2. AND N IS 1 TO 2, SAID INGREDIENTS BEING PRESENT IN THE RATIO OF ABOUT 1 PART BY WEIGHT OF SAID NITRITE TO 0.05-20 PARTS BY WEIGHT EACH OF SAID AMIDE AND SAID SALT. 